African Americans resented such questions and pushed the White House to integrate the troops.

During World War II, many blacks supported what they called the “Double V” campaign, SoRelle said — one “V” for victory abroad, and one for victory in eliminating “the anti-democratic, second-class citizenship that most of them faced in Jim Crow America.”

There also were fears during World War II that gays could be more easily pressured to give up secrets during prisoner-of-war interrogations, SoRelle said. Lately, the argument has been that allowing gays to serve openly would disrupt morale and hurt efficiency — again, echoes from the concerns raised about integrating blacks.

Those concerns proved unfounded with African Americans. In 1944, Lt. Gen. Alexander Vandegrift, commandant of the Marines, said “The Negro Marines are no longer on trial. They are Marines, period.”

After Truman signed his executive order, it took two years for desegregation plans to be adopted and another three for almost all African Americans in the Army to serve in integrated units — and only then, some historian believe, because shortages of white troops during the Korean War accelerated the process.

Navy ships weren’t fully integrated until the 1970s.

But the momentum was unmistakable.

“It didn’t make the Brown decision inevitable, but it did make it possible,” said Podair, the Lawrence College historian, referring to the 1954 U.S. Supreme Court decision ending segregation in public schools.

Which raises the question that many in the gay community have been asking since Tuesday: What has the end of “don’t ask, don’t tell” made possible?

"Just one of us"

Historians are more comfortable with the past than the future, but SoRelle offered this guess:

“Following a period of either celebration or complaint from various quarters, the matter (of gays in the military) will disappear as a serious policy concern. And in a generation from now, most Americans will realize that … change can occur in the United States without destroying the very fabric of our nation’s institutions.”

Wilson, the lawyer, thinks one impact to watch for is in public perceptions.

“Having openly gay people in the military will create change, as more and more people see them and realize ‘Oh, you’re just one of us,’ ” she said.

Bornhoft, the retired colonel, agreed. He was working at West Point when women were first admitted there, and he saw attitudes and behaviors changing. Frat-boy antics gave way to respect, he said.

“Many people think they’ve never met anyone who was gay, or they have the stereotype of the limp-wristed sissy not capable of doing anything,” he said. “Now they’ll start to see people in uniform, serving in one of the most respected segments of our country, the military.

“They’ll see people who face the same challenges as they do, who are pursuing the same kinds of goals — raising a family, going to the mall, volunteering, coaching their kids’ soccer teams. All those things that make up the fabric of American life. And they’ll go, ‘Wow, maybe I’ve been wrong about this. Maybe my beliefs about gays aren’t valid.’ And as that happens, things like marriage equality will happen at an accelerated pace.”